4-34
MPC565/MPC566 Reference Manual
MOTOROLA
BBC Programming Model
19
ETRE
Exception Table Relocation Enable
0 Exception Table Relocation is off: BBC does NOT map exception addresses.
1 Exception Table Relocation is on: BBC maps exception addresses to a table holding branch
instructions two memory words apart from each other.
The reset value is taken from the reset configuration word bit #19.
20
EIR
Enhanced External Interrupt Relocation Enable— This bit activates the external interrupt
relocation table mechanism. This bit is independent from the value of ETRE bit, but if EIR and
ETRE are enabled, the mapping of external interrupt will be via EIR.
0 EIR function is disabled.
1 EIR function is active.
21
EN_
COMP 1
Enable COMPression — This bit enables the operation of the MPC566 in “Compression ON”
mode. The default state is disabled.
0 “Decompression ON” mode is disabled. The MPC565/MPC566 operates only in
“Decompression OFF” mode.
1 “Decompression ON” mode is enabled. The MPC566 may operate with both “Decompression
ON” and “Decompression OFF” modes.
The bit value is determined by reset configuration word, bit #21.
22
EXC_
COMP1
Exception Compression — This bit determines the operation of the MPC565/MPC566 with
exceptions. If this bit is set, the MPC566 assumes that the all exception routine codes are
compressed; otherwise it is assumed that all exception routine codes are not compressed. The
reset value is determined by reset configuration word bit #22.
0 The MPC565/MPC566 assumes that exception routines are noncompressed
1 The MPC566 assumes that all exception routines are compressed.
This bit has effects only when the EN_COMP bit is set.
23
DECOMP_
SC_EN1
DECOMPression Show Cycle ENable — This bit determines the way the MPC565/MPC566
executes instruction show cycles.
The reset value is determined by configuration word bit #21. For further details regarding show
0 Decompression Show Cycles do not include the bit pointer.
1 Decompression Show Cycles include the bit pointer information on the data bus.
24:25
OERC[0:1] Other Exceptions Relocation Control — These bits have effect only if ETRE was enabled; See
00: offset 0
01: offset 64 Kbytes
10: offset 512 Kbytes
11: offset to 0x003FE000 (SRAM start address)
The reset value is determined by reset configuration word bits #24, #25
26
BTEE
Branch Target Entries Enable — This bit enables Branch Target Entries of BTB operation
0 BTE operation is disable
1
BTE operation is enable.
27:29
—
Reserved.
NOTE: Bit 27 was BCMEE and should be written as 0.
Table 4-4. BBCMCR BBC Module Configuration Register
Bit Descriptions (continued)
Bit(s)
Name
Description